| year | pollutant_name | index |
|---|---|---|
| 1990 | SOx excluding international shipping | 100.0 |
| 1991 | SOx excluding international shipping | 95.4 |
| 1992 | SOx excluding international shipping | 96.3 |
| 1993 | SOx excluding international shipping | 94.4 |
| 1994 | SOx excluding international shipping | 91.1 |
| 1995 | SOx excluding international shipping | 78.7 |
| 1996 | SOx excluding international shipping | 71.0 |
| 1997 | SOx excluding international shipping | 53.5 |
| 1998 | SOx excluding international shipping | 53.6 |
| 1999 | SOx excluding international shipping | 49.5 |
| 2000 | SOx excluding international shipping | 41.9 |
| 2001 | SOx excluding international shipping | 39.4 |
| 2002 | SOx excluding international shipping | 34.0 |
| 2003 | SOx excluding international shipping | 34.2 |
| 2004 | SOx excluding international shipping | 32.5 |
| 2005 | SOx excluding international shipping | 26.6 |
| 2006 | SOx excluding international shipping | 25.6 |
| 2007 | SOx excluding international shipping | 23.1 |
| 2008 | SOx excluding international shipping | 20.4 |
| 2009 | SOx excluding international shipping | 18.1 |
| 2010 | SOx excluding international shipping | 15.4 |
| 2011 | SOx excluding international shipping | 14.4 |
| 2012 | SOx excluding international shipping | 12.5 |
| 2013 | SOx excluding international shipping | 12.5 |
| 2014 | SOx excluding international shipping | 12.7 |
| 2015 | SOx excluding international shipping | 11.2 |
| 2016 | SOx excluding international shipping | 11.1 |
| 2017 | SOx excluding international shipping | 12.6 |