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          532        200 
1992          936        367 
1993         1672        611 
1994         2339        844 
1995         4430       1529 
1996         3605       1266 
1997         2337        797 
1998        23345       9841 
1999        14646       5620 
2000        40829      16957 
2001        41928      16362 
2002        33163      14800 
2003        62268      25810 
2004        48889      18762 
2005        87546      26873 
2006       113382      36166 
2007       208480      63790 
2008       129742      36856 
2009       105331      29569 
2010       122417      33945 
2011       184724      51055 
2012       171063      47318 
2013       267229      75767 
2014       665688     169746 
2015       778186     206190 
2016       575186     153998 
2017       556261     152604 
2018       407771     114420 
2019       925167     225937 
2020       717010     184084 
2021       944305     226464 
2022       692329     198058 
2023       638798     183808 
2024        17598       5483