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          492        186 
1992          767        309 
1993         1356        504 
1994         1752        642 
1995         3306       1150 
1996         3335       1173 
1997         2291        783 
1998        23123       9754 
1999        14437       5534 
2000        40030      16600 
2001        40883      15928 
2002        32112      14350 
2003        59985      24911 
2004        47376      18177 
2005        83255      25615 
2006       107464      34427 
2007       197424      60796 
2008       118938      33931 
2009        97843      27537 
2010       112709      31392 
2011       166900      46227 
2012       157559      43625 
2013       233746      66505 
2014       577290     147251 
2015       759076     198487 
2016       672668     174160 
2017       573809     154992 
2018       370947     104088 
2019       895397     218845 
2020       646959     164984 
2021       866275     206487 
2022       641937     183788 
2023       586064     167645 
2024       490973     141948