| Year | Mean Selenium Levels | ||||||||||
| Overall | Males | Females | Asian | Black | Mexican American | Other | Other Hispanic | White | At or Below Poverty Line | Above Poverty Line | |
| 1999-2000 | 108.020 | 108.630 | 107.280 | - | 105.260 | 108.702 | 120.270 | 104.450 | 109.530 | 106.653 | 109.160 |
| 2001-2002 | - | - | - | - | - | - | - | - | - | - | - |
| 2003-2004 | - | - | - | - | - | - | - | - | - | - | - |
| 2005-2006 | - | - | - | - | - | - | - | - | - | - | - |
| 2007-2008 | - | - | - | - | - | - | - | - | - | - | - |
| 2009-2010 | - | - | - | - | - | - | - | - | - | - | - |
| 2011-2012 | 166.159 | 166.655 | 165.630 | 165.003 | 165.247 | 167.174 | 166.373 | 163.683 | 169.216 | 166.655 | 165.630 |
| 2013-2014 | 167.800 | 166.940 | 168.753 | 163.870 | 168.795 | 164.888 | 170.219 | 166.737 | 170.290 | 166.940 | 168.753 |
| 2015-2016 | 166.400 | 164.593 | 168.394 | 164.016 | 167.415 | 167.870 | 164.672 | 162.894 | 166.802 | 164.593 | 168.394 |
| 2017-2020 | 160.895 | 161.055 | 160.717 | 158.395 | 160.841 | 163.167 | 163.353 | 156.031 | 161.080 | 161.839 | 160.778 |