1 - Jan

2 - Feb

3 - Mar

4 - Apr

5 - May

6 - Jun

7 - Jul

8 - Aug

9 - Sep

10 - Oct

11 - Nov

12 - Dec

Array
(
    [Jan] => 1
    [Feb] => 2
    [Mar] => 3
    [Apr] => 4
    [May] => 5
    [Jun] => 6
    [Jul] => 7
    [Aug] => 8
    [Sep] => 9
    [Oct] => 10
    [Nov] => 11
    [Dec] => 12
)