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         2258        815 
1995         3362       1169 
1996         3573       1255 
1997         2326        793 
1998        23237       9798 
1999        14506       5562 
2000        40399      16762 
2001        42957      16657 
2002        32422      14492 
2003        61023      25306 
2004        47840      18351 
2005        84863      26095 
2006       110286      35249 
2007       203031      62303 
2008       124256      35377 
2009       100856      28354 
2010       117461      32640 
2011       175740      48604 
2012       163490      45212 
2013       252355      71399 
2014       598327     153338 
2015       724292     192158 
2016       708687     183364 
2017       598622     161600 
2018       393682     110328 
2019       927516     227705 
2020       680440     174218 
2021       891215     213242 
2022       661811     189274 
2023       599104     172508 
2024       262869      76177