c# – 如何在LINQ select中访问循环索引？

var customers = from cust in Customers
    group cust by new {cust.Country} into grouping
    select new
    {
        Country = grouping.Key.Country,Customers = grouping
    };

customers.ToList().ForEach(g => 
    Console.WriteLine("{0} has {1} customers: {2}",g.Country,g.Customers.Count(),String.Join(",",g.Customers.Select(x => "#. " + x.CompanyName).ToArray())
    ));

customers.Dump();

产生这些结果：

Argentina has 3 customers: #. Cactus Comidas para llevar,#. Océano Atlántico Ltda.,#. Rancho grande
Austria has 2 customers: #. Ernst Handel,#. Piccolo und mehr
Belgium has 2 customers: #. Maison Dewey,#. Suprêmes délices
Brazil has 9 customers: #. Comércio Mineiro,#. Familia Arquibaldo,#. Gourmet Lanchonetes,#. Hanari Carnes,#. Que Delícia,#. Queen Cozinha,#. Ricardo Adocicados,#. Tradi??o Hipermercados,#. Wellington Importadora
Canada has 3 customers: #. Bottom-Dollar Markets,#. Laughing Bacchus Wine Cellars,#. Mère Paillarde
Denmark has 2 customers: #. Simons bistro,#. Vaffeljernet
...

如何用索引/计数替换“#”,以便得到如下结果：

Argentina has 3 customers: 1. Cactus Comidas para llevar,2. Océano Atlántico Ltda.,3. Rancho grande
...