Year Observations     Objects
1858            3          3 
1889            1          1 
1901            1          1 
1920            6          2 
1950            2          1 
1951            6          3 
1953           14          8 
1954           12          5 
1955           14          7 
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          228         81 
1991          867        310 
1992          719        292 
1993         1273        474 
1994         1625        598 
1995         2848        997 
1996         2865       1014 
1997         2870        980 
1998        24600      10341 
1999        13446       5129 
2000        37736      15564 
2001        43258      17026 
2002        40466      16969 
2003        60212      24610 
2004        46930      17908 
2005       312138     140199 
2006       338275     150698 
2007       198159      61238 
2008       115759      33079 
2009        97158      27235 
2010       147448      39272 
2011       156601      42766 
2012       184670      40883 
2013       242957      61686 
2014       545688     133940 
2015       785021     204260 
2016       625815     161474 
2017       541806     147098 
2018       330168      92864 
2019       840701     205407 
2020       574353     145520 
2021       785152     185203 
2022       595907     170623 
2023       539625     154401 
2024       591059     169853 
2025       612633     174987 
2026        10158       3000