| year | pollutant_name | index |
|---|---|---|
| 1990 | SOx excluding international shipping | 100.0 |
| 1991 | SOx excluding international shipping | 95.2 |
| 1992 | SOx excluding international shipping | 97.0 |
| 1993 | SOx excluding international shipping | 96.1 |
| 1994 | SOx excluding international shipping | 93.0 |
| 1995 | SOx excluding international shipping | 80.6 |
| 1996 | SOx excluding international shipping | 74.8 |
| 1997 | SOx excluding international shipping | 58.6 |
| 1998 | SOx excluding international shipping | 59.6 |
| 1999 | SOx excluding international shipping | 56.8 |
| 2000 | SOx excluding international shipping | 37.6 |
| 2001 | SOx excluding international shipping | 36.5 |
| 2002 | SOx excluding international shipping | 31.0 |
| 2003 | SOx excluding international shipping | 32.1 |
| 2004 | SOx excluding international shipping | 30.6 |
| 2005 | SOx excluding international shipping | 22.6 |
| 2006 | SOx excluding international shipping | 24.0 |
| 2007 | SOx excluding international shipping | 22.2 |
| 2008 | SOx excluding international shipping | 19.6 |
| 2009 | SOx excluding international shipping | 20.1 |
| 2010 | SOx excluding international shipping | 14.4 |
| 2011 | SOx excluding international shipping | 14.3 |
| 2012 | SOx excluding international shipping | 13.1 |
| 2013 | SOx excluding international shipping | 12.8 |
| 2014 | SOx excluding international shipping | 12.2 |
| 2015 | SOx excluding international shipping | 11.7 |