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          770        310 
1993         1356        504 
1994         1752        642 
1995         3315       1153 
1996         3370       1185 
1997         2291        783 
1998        23130       9757 
1999        14444       5537 
2000        40047      16606 
2001        40890      15931 
2002        32123      14355 
2003        60031      24928 
2004        47398      18186 
2005        83340      25640 
2006       107600      34466 
2007       197660      60863 
2008       119187      33999 
2009        97937      27565 
2010       112914      31446 
2011       167203      46307 
2012       157707      43665 
2013       234410      66689 
2014       576992     147216 
2015       707090     186455 
2016       673344     174328 
2017       574751     155217 
2018       371635     104276 
2019       896496     219141 
2020       647805     165216 
2021       866986     206689 
2022       642505     183953 
2023       586043     167773 
2024       474194     137744