Album sales at the nation’s record stores made an expected post-holiday retreat, according to SoundScan figures, which are provided by a record label source. Most titles fell dramatically last week from Christmas highs, while a few managed impressive chart jumps without increased sales.Back on top of the tally is L.A. rapper Snoop Doggy Dogg, whose first Interscope set, “Doggystyle,” sold some 270,000 copies, off from the previous week’s 407,000. That album displaced Mariah Carey’s Columbia title, “Music Box,” with sales at 260,000, down from 505,000. Also selling 260,000 copies was Pearl Jam’s sophomore Epic effort, “Vs.,” after moving nearly 472,000 last week. After a No. 27 debut last week, MCA hip-hop/doo-wop act Jodeci leapt to No. 8 , despite selling 4,300 fewer records than last week. Boston rockers Aerosmith saw their current Geffen album “Get a Grip” return to the top 10, moving from No. 17 to 10 on the strength of the band’s new “Amazing” single and video. Of the week’s notable chart free falls: Frank Sinatra’s Capitol release “Duets” from No. 5 to 20, with unit sales eroding some 70%; Billy Joel’s “River of Dreams” (Columbia) flowed down to 22 from No. 10; Guns N’ Roses’ new Geffen album, “The Spaghetti Incident?,” continued to disappoint, sliding from 20 to 27 .