year    vol
1  2011 619.60
2  1986 606.49
3  1984 576.25
4  1983 528.81
5  2017 451.87
6  1997 435.29
7  1950 435.13
8  1971 433.93
9  1952 399.21
10 1972 382.10
11 1965 377.77
12 1980 350.59
13 1999 348.55
14 1998 348.18
15 1951 323.34
16 1982 312.78
17 1957 276.66
18 1936 273.72
19 1974 273.10
20 1985 272.91
21 2005 270.10
22 1975 269.92
23 1962 266.93
24 1996 263.70
25 1967 258.00
26 1976 247.50
27 1956 242.83
28 1993 240.54
29 1947 236.97
30 1969 234.24
31 1946 233.01
32 1929 230.84
33 1948 225.23
34 1943 223.80
35 1938 221.48
36 1928 218.58
37 1964 214.05
38 1978 213.87
39 1973 205.56
40 1995 205.00
41 2009 197.10
42 1937 196.58
43 1944 196.48
44 1932 194.00
45 1927 193.08
46 1949 163.22
47 2006 147.97
48 1966 146.04
49 1968 140.74
50 1958 130.55
51 1942 127.92
52 1945 122.88
53 2008 120.54
54 2010 112.82
55 1930 112.21
56 1970  97.98
57 1953  96.70
58 1987  91.79
59 2014  91.19
60 1933  90.12
61 1939  85.36
62 1979  85.24
63 2015  77.30
64 1991  66.29
65 1960  61.23
66 1941  59.46
67 1963  57.98
68 1959  54.35
69 1935  52.93
70 1988  49.58
71 2000  48.81
72 1955  48.20
73 1989  44.36
74 1954  43.33
75 2012  39.45
76 1981  38.16
77 2007  34.77
78 1994  22.10
79 2013  21.57
80 1992  17.44
81 2001  16.44
82 1931  16.08
83 2004  15.58
84 1990  14.24
85 2003  11.18
86 2002   8.05
87 1961   7.85
88 1940   5.57
89 1977   5.18
90 1934   3.31