Year Observations     Objects
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           12          6 
1956            8          4 
1960            6          3 
1974            2          1 
1975            2          1 
1976            8          4 
1977            2          1 
1978           12          5 
1981           18          5 
1982           13          7 
1983            8          4 
1984            2          1 
1985            8          4 
1986            4          2 
1987            2          1 
1988           38         18 
1990          213         76 
1991          856        306 
1992          653        269 
1993         1176        442 
1994         1481        553 
1995         2350        830 
1996         2614        928 
1997         2480        847 
1998        23904       8540 
1999        12798       4882 
2000        36242      14881 
2001        41357      16238 
2002        34910      14935 
2003        56786      23265 
2004        44739      17040 
2005       302502     136345 
2006       330192     147474 
2007       191438      59325 
2008       107337      30634 
2009        87711      24551 
2010       135451      36086 
2011       142210      38700 
2012       169825      36798 
2013       223522      56219 
2014       470024     116642 
2015       708047     185176 
2016       598512     154680 
2017       502473     136605 
2018       300137      84886 
2019       801327     196257 
2020       524906     133014 
2021       706188     165229 
2022       548667     157395 
2023       508299     145635 
2024       548181     157577 
2025       522939     148748 
2026       367823      87544