| Views | |
| Effects of per-vehicle entrance fees on U.S. National Park visitation rates | 336 |
| November 2012 | December 2012 | January 2013 | February 2013 | March 2013 | April 2013 | May 2013 | |
| Effects of per-vehicle entrance fees on U.S. National Park visitation rates | 16 | 18 | 23 | 16 | 13 | 17 | 13 |
| Views | |
| MP_sdf9_a_200709.pdf | 520 |
| MP_sdf9_a_200709.pdf.txt | 2 |
| Views | |
| United States of America | 187 |
| China | 80 |
| Russian Federation | 29 |
| Japan | 17 |
| Ukraine | 12 |
| Germany | 2 |
| Malaysia | 2 |
| Netherlands | 2 |
| Aruba | 1 |
| Colombia | 1 |
| Views | |
| Beijing | 60 |
| Mountain View | 35 |
| Bozeman | 20 |
| Moscow | 15 |
| Redwood City | 15 |
| Redmond | 10 |
| Needham Heights | 8 |
| San Francisco | 5 |
| Athens | 4 |
| Spokane | 3 |