Year Observations     Objects
1950            2          1 
1951            6          3 
1953            4          2 
1954            2          1 
1955            4          2 
1956            2          1 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978            8          3 
1981            4          2 
1982           12          6 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990           32         14 
1991          471        179 
1992          743        301 
1993         1308        487 
1994         1681        617 
1995         3054       1066 
1996         2980       1053 
1997         1863        643 
1998        21688       9220 
1999        13531       5190 
2000        38626      15969 
2001        39456      15326 
2002        32271      14295 
2003        57762      24034 
2004        46350      17783 
2005        81429      25066 
2006       105103      33734 
2007       191904      59312 
2008       112460      32200 
2009        93205      26270 
2010       141269      38135 
2011       158277      43901 
2012       149501      41422 
2013       221461      63089 
2014       564657     143857 
2015       798322     210093 
2016       659403     171360 
2017       554789     150177 
2018       351935      98868 
2019       864211     210946 
2020       617639     157187 
2021       831273     197394 
2022       620714     177666 
2023       558915     159861 
2024       617601     177934 
2025       211240      60389