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        23234       9797 
1999        14506       5562 
2000        40399      16762 
2001        42953      16655 
2002        32419      14491 
2003        61012      25302 
2004        47840      18351 
2005        84860      26094 
2006       110242      35235 
2007       202981      62290 
2008       124216      35366 
2009       100809      28341 
2010       117406      32626 
2011       175639      48578 
2012       163440      45198 
2013       252128      71337 
2014       598055     153268 
2015       724090     192101 
2016       708413     183294 
2017       598649     161594 
2018       393524     110286 
2019       927165     227617 
2020       679381     173980 
2021       890960     213171 
2022       661695     189239 
2023       615120     174192 
2024       265398      76928