The last time Arbitron conducted a radio survey for the Sherman/Dension market was 1979. (Though its county-by-county measurements still exist for subscribers.)
The small-market focused Eastlan company has measured the "Sherman/Denison/Durant" market for the last four years on an annual basis. The spring 2014 12+ numbers:
1. KMAD Classic Rock 10.2
2. WBAP N/T 9.9
3. KMKT Country 7.4
4. KQDR CHR 4.4
5. KLBC Country 4.1
6. KLAK AC 3.4
7. KHYI Americana 3.1
8. KKAJ Country 3.0
9. KDGE Alternative 2.4
9. KJIM Adult Standards 2.4