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         2326        839 
1995         3776       1308 
1996         3578       1257 
1997         2335        796 
1998        23274       9813 
1999        14538       5575 
2000        40499      16806 
2001        43092      16711 
2002        32561      14556 
2003        61343      25429 
2004        48067      18437 
2005        85688      26341 
2006       111104      35495 
2007       204785      62777 
2008       125863      35810 
2009       102447      28784 
2010       118981      33036 
2011       178556      49378 
2012       166771      45933 
2013       257925      72903 
2014       647199     163742 
2015       744545     197116 
2016       572884     152859 
2017       610480     163747 
2018       402090     112681 
2019       943004     230900 
2020       692468     177572 
2021       899373     215389 
2022       667583     190942 
2023       607298     174846 
2024       200335      57379