Graph with 3 different time periods?

Hello,

I need to plot a graph of CO2 sequestered by carbon sinks (ppmv) over time, but want to show the data in three separate time periods:
1960-1975
1975-1990
1990-2011

I want it on the same graph, but with three different colors and 3 different legend titles. Please help!
The data looks like this:

Year ppmv
1960
1961 1.16
1962 1.48
1963 1.63
1964 1.57
1965 1.58
1966 0.95
1967 1.61
1968 1.58
1969 1.11
1970 1.44
1971 1.85
1972 1.64
1973 0.80
1974 2.06
1975 1.77
1976 1.85
1977 1.38
1978 1.34
1979 1.75
1980 1.14
1981 1.65
1982 1.85
1983 1.39
1984 1.74
1985 1.90
1986 1.94
1987 1.72
1988 1.38
1989 2.11
1990 2.33
1991 2.43
1992 2.64
1993 2.86
1994 2.13
1995 1.81
1996 2.06
1997 2.64
1998 1.07
1999 1.95
2000 2.53
2001 2.42
2002 1.78
2003 1.82
2004 2.58
2005 2.31
2006 2.63
2007 2.80
2008 2.74
2009 3.13
2010 2.79
2011 3.30

Any direction would be appreciated!

Wow that's great thank you so much!

Do you know how to add a trendline so that it only displays the trendline over that period?
I wanted to add 3 trendlines but not have them overlap...

Brilliant, thanks again! What a good forum.