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         2128        771 
1995         3351       1165 
1996         3567       1253 
1997         2326        793 
1998        23197       9782 
1999        14488       5555 
2000        40219      16680 
2001        41137      16029 
2002        32221      14409 
2003        60563      25131 
2004        47640      18272 
2005        84134      25881 
2006       109028      34882 
2007       200604      61651 
2008       122011      34762 
2009        99326      27942 
2010       115289      32071 
2011       171257      47399 
2012       160299      44365 
2013       242800      68967 
2014       584413     150120 
2015       708127     187871 
2016       679394     176409 
2017       578915     156588 
2018       380594     106742 
2019       908307     222526 
2020       672938     171528 
2021       873815     208434 
2022       656954     187896 
2023       601500     171787 
2024       310736      90056