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         1669        610 
1994         2329        840 
1995         3799       1316 
1996         3578       1257 
1997         2335        796 
1998        23277       9814 
1999        14542       5577 
2000        40524      16818 
2001        43121      16725 
2002        32594      14571 
2003        61413      25458 
2004        48157      18471 
2005        85872      26392 
2006       111285      35549 
2007       205114      62863 
2008       126202      35901 
2009       102698      28850 
2010       119256      33108 
2011       179068      49519 
2012       166222      45995 
2013       258826      73149 
2014       652408     164317 
2015       744662     197600 
2016       573217     152962 
2017       611430     163955 
2018       404451     113373 
2019       942182     230476 
2020       694410     178111 
2021       901697     215979 
2022       669399     191455 
2023       610184     175629 
2024       200814      57767