Here's a listing of the top 100 most used fonts from the Fonts.com Web Fonts service for June 2014:

Trade Gothic

Neue Helvetica

Avenir Next

Univers

Avenir

Proxima Nova

Frutiger

Helvetica

Futura

Gill Sans

Museo Sans

DIN Next

Linotype Univers

Century Gothic

Museo Slab

Klint

Arial

ITC Avant Garde Gothic

Chaparral

Neo Sans

Rockwell

Eurostile LT

Myriad

Motoya Birch

ITC Legacy Serif

ITC Lubalin Graph

Univers Next

VAG Rounded

Soho Gothic

ITC Century

ITC Caslon No. 224

Linotype Sketch

ITC Franklin Gothic

Optima

ITC Legacy Square Serif

Trade Gothic Next

Neue Frutiger

Soho

Swiss 721

Swift

Neue Helvetica eText

ITC Charter

Frutiger Next

ITC Officina Serif

Helvetica World

Gill Sans Infant

Minion

Bodoni LT

Lexia

Bookman Old Style

Adobe Garamond

Linotype Didot

ITC Officina Sans

Slate

Humanist 777

PMN Caecilia

ITC Eras

Copperplate Gothic

ITC Conduit

Calibri

Orator

Auriol

Trade Gothic Next Soft Rounded

Rotis Sans Serif

ITC Stone Informal

Novecento

ITC American Typewriter Hellenic

Rotis II Sans

ITC American Typewriter

Droid Sans Mono

ITC Fenice

Bembo

Droid Serif

C Hei 2 PRC

Egyptienne F

Brandon Grotesque

Adobe Caslon

Monotype News Gothic

Monotype Goudy

Caslon Classico

M Elle PRC

C Hei PRC

M Lady PRC

M Stiff Hei PRC

Baskerville Classico

Azbuka

Glypha

ITC Stone Sans

ITC Stone Serif

Twentieth Century

Delima

Plantin

Francker

Linotype Feltpen

Cachet

Comic Strip

Akko

Droid Sans

Alternate Gothic

Sackers Gothic