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          503        190 
1992          936        367 
1993         1666        609 
1994         2326        839 
1995         3429       1192 
1996         3576       1256 
1997         2329        794 
1998        23263       9808 
1999        14524       5569 
2000        40476      16796 
2001        43050      16693 
2002        32486      14522 
2003        61226      25381 
2004        47966      18396 
2005        85382      26251 
2006       110831      35415 
2007       204029      62571 
2008       125181      35628 
2009       101815      28611 
2010       118298      32859 
2011       177514      49091 
2012       164895      45569 
2013       256350      72393 
2014       610852     155963 
2015       730456     193513 
2016       571935     152401 
2017       603534     162532 
2018       397252     111133 
2019       932425     228512 
2020       687243     176107 
2021       895154     214282 
2022       664543     190076 
2023       603612     173804 
2024       220382      63679