Why isn’t my GPA higher?

The Registrar has posted fall term median grades. The bottom three departments on the chart alphabetically:

02F SPAN-001-01 18 A-

02F SPAN-001-02 22 B

02F SPAN-001-03 18 B+

02F SPAN-001-04 14 A-

02F SPAN-002-01 17 A-

02F SPAN-002-02 16 A-

02F SPAN-002-03 21 A-

02F SPAN-002-04 21 B+

02F SPAN-002-05 16 A-

02F SPAN-002-06 15 A-

02F SPAN-003-01 22 B+

02F SPAN-003-02 17 A-

02F SPAN-003-03 22 A-

02F SPAN-009-01 20 B+

02F SPAN-009-02 28 A-

02F SPAN-009-03 20 A-/B +

02F SPAN-030-01 17 A-

02F SPAN-037-01 19 A-

02F SPAN-056-01 13 A-

02F SPAN-058-01 11 A-

02F SPAN-079-01 18 A-

02F SPEE-027-01 16 A-

02F THEA-018-01 26 A

02F THEA-030-01 15 A-

02F THEA-030-02 16 A

02F THEA-040-01 19 A

02F THEA-045-01 11 A-

02F WGST-010-01 21 A

02F WGST-025-01 15 A

02F WGST-030-01 70 A-

02F WGST-032-01 13 B+

02F WGST-035-01 38 A

02F WGST-037-01 63 A-

02F WGST-043-01 24 A

02F WGST-047-01 16 A