HOLLYWOOD — CBS reality series “Big Brother” went out a winner Thursday, topping its hour in key demos and improving on the finale of its first edition of last summer.

According to preliminary nationals from Nielsen, Thursday’s finale — which saw Miami doctor Will Kirby win the top $500,000 prize — grabbed the show’s largest aud of the summer (12.3 million viewers) and won its 10 o’clock hour in adults 18-49 (6.0/15) and adults 18-34 (5.8/16) while finishing second in adults 25-54 (6.1/14).

These are the best demo scores for any CBS program since the season finale of “Everybody Loves Raymond” on May 21. It’s also the best demo perf for any hour of “Big Brother” over the last two summers that did not air immediately following “Survivor.” (Five of last summer’s “Brother” episodes aired on Wednesdays after the juggernaut reality series.)

Compared with last summer’s finale, Thursday’s wrap was up 10% in total viewers, 15% in adults 25-54, 20% in adults 18-49 and 31% in adults 18-34.

After winning 34% of its half-hours in adults 18-49 last summer, “Big Brother” won 64% of its half-hours this year, including 31 of its final 36.