The GAF score directly translates to the VASRD rating schedule. The lower your GAF score the higher rating comes back. With a GAF of 59 you are nearly at 60 which would then put you at the moderate state and thus warrant a 30% rating.
Here are the GAF scores and methodology behind them:
100
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91 Superior functioning in a wide range of activities, life’s problems never seem to get out of hand, is sought out by others because of his or her many positive qualities. No symptoms.
90
|
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81 Absent or minimal symptoms (e.g., mild anxiety before an exam), good functioning in all areas, interested and involved in a wide range of activities, socially effective, generally satisfied with life, no more than everyday problems or concerns (e.g., an occasional argument with family members).
80
|
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71 If symptoms are present, they are transient and expectable reactions to psychosocial stressors (e.g., difficulty concentrating after family argument); no more than slight impairment in social, occupational, or school functioning (e.g., temporarily falling behind in schoolwork).
70
|
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61 Some mild symptoms (e.g., depressed mood and mild insomnia) OR some difficulty in social, occupational, or school functioning (e.g., occasional truancy, or theft within the household), but generally functioning pretty well, has some meaningful interpersonal relationships.
60
|
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51 Moderate symptoms (e.g., flat affect and circumstantial speech, occasional panic attacks) OR moderate difficulty in social, occupational, or school functioning (e.g., few friends, conflicts with peers or co-workers).
50
|
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41 Serious symptoms (e.g., suicidal ideation, severe obsessional rituals, frequent shoplifting) OR any serious impairment in social, occupational, or school functioning (e.g., no friends, unable to keep a job).
40
|
|
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31 Some impairment in reality testing or communication (e.g., speech is at times illogical, obscure, or irrelevant) OR major impairment in several areas, such as work or school, family relations, judgment, thinking, or mood (e.g., depressed man avoids friends, neglects family, and is unable to work; child frequently beats up younger children, is defiant at home, and is failing at school).
30
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21 Behavior is considerably influenced by delusions or hallucinations OR serious impairment, in communication or judgment (e.g., sometimes incoherent, acts grossly inappropriately, suicidal preoccupation) OR inability to function in almost all areas (e.g., stays in bed all day, no job, home, or friends)
20
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11 Some danger of hurting self or others (e.g., suicide attempts without clear expectation of death; frequently violent; manic excitement) OR occasionally fails to maintain minimal personal hygiene (e.g., smears feces) OR gross impairment in communication (e.g., largely incoherent or mute).
10
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1 Persistent danger of severely hurting self or others (e.g., recurrent violence) OR persistent inability to maintain minimal personal hygiene OR serious suicidal act with clear expectation of death.
0
Inadequate information.
And here is the rating guidlines from the VASRD
General Rating Formula for Mental Disorders:
Total occupational and social impairment, due to such symptoms as:
gross impairment in thought processes or communication;
persistent delusions or hallucinations; grossly inappropriate
behavior; persistent danger of hurting self or others; intermittent
inability to perform activities of daily living (including maintenance
of minimal personal hygiene); disorientation to time or place; memory
loss for names of close relatives, own occupation, or own name .................... 100
Occupational and social impairment, with deficiencies in most areas,
such as work, school, family relations, judgment, thinking, or mood,
due to such symptoms as: suicidal ideation; obsessional rituals
which interfere with routine activities; speech intermittently illogical,
obscure, or irrelevant; near-continuous panic or depression affecting
the ability to function independently, appropriately and effectively;
impaired impulse control (such as unprovoked irritability with periods
of violence); spatial disorientation; neglect of personal appearance and
hygiene; difficulty in adapting to stressful circumstances (including
work or a worklike setting); inability to establish and maintain
effective relationships ........................................................................................ 70
Occupational and social impairment with reduced reliability and
productivity due to such symptoms as: flattened affect; circumstantial,
circumlocutory, or stereotyped speech; panic attacks more than once
a week; difficulty in understanding complex commands; impairment
of short- and long-term memory (e.g., retention of only highly learned
material, forgetting to complete tasks); impaired judgment; impaired
abstract thinking; disturbances of motivation and mood; difficulty in
establishing and maintaining effective work and social relationships ............... 50
Occupational and social impairment with occasional decrease in work
efficiency and intermittent periods of inability to perform occupational
tasks (although generally functioning satisfactorily, with routine
behavior, self-care, and conversation normal), due to such symptoms
as: depressed mood, anxiety, suspiciousness, panic attacks (weekly or
less often), chronic sleep impairment, mild memory loss (such as
forgetting names, directions, recent events) ...................................................... 30
Occupational and social impairment due to mild or transient symptoms
which decrease work efficiency and ability to perform occupational
tasks only during periods of significant stress, or; symptoms controlled
by continuous medication .................................................................................. 10
A mental condition has been formally diagnosed, but symptoms are not
severe enough either to interfere with occupational and social
functioning or to require continuous medication.................................................. 0
By the time the GAF score gets to the VA, it's simply a number--the score or test isn't broken down in a detailed manner showing specifically how each question was answered by the SM. 
